Which of the following is an example of physical weathering?
- A. The cracking of a rock caused by the freezing and thawing of water.
- B. Sediments being transported in a stream.
- C. A sandbar forming in a stream.
- D. Acid rain dissolving a statue.
Correct Answer & Rationale
Correct Answer: A
Physical weathering involves the mechanical breakdown of rocks without changing their chemical composition. Option A exemplifies this, as the freezing and thawing of water causes rocks to crack due to the expansion of ice, a clear physical process. Option B describes sediment transport, which is a process related to erosion rather than weathering. Option C refers to the formation of a sandbar, a depositional feature resulting from sediment accumulation, not weathering. Option D involves chemical weathering, where acid rain alters the chemical structure of the statue, distinguishing it from the physical processes in option A.
Physical weathering involves the mechanical breakdown of rocks without changing their chemical composition. Option A exemplifies this, as the freezing and thawing of water causes rocks to crack due to the expansion of ice, a clear physical process. Option B describes sediment transport, which is a process related to erosion rather than weathering. Option C refers to the formation of a sandbar, a depositional feature resulting from sediment accumulation, not weathering. Option D involves chemical weathering, where acid rain alters the chemical structure of the statue, distinguishing it from the physical processes in option A.
Other Related Questions
Which THREE of the following are considered sources of freshwater?
- A. Rivers
- B. Aquifers
- C. Oceans
- D. Glaciers
Correct Answer & Rationale
Correct Answer: A,B,D
Rivers, aquifers, and glaciers are all significant sources of freshwater. Rivers provide accessible water for ecosystems and human use, while aquifers store water underground, making it available for wells and springs. Glaciers, as large ice formations, hold substantial freshwater reserves that can feed rivers and lakes as they melt. In contrast, oceans are primarily saline and not suitable for direct human consumption or most agricultural uses. Therefore, they do not qualify as sources of freshwater, making options A, B, and D the correct choices.
Rivers, aquifers, and glaciers are all significant sources of freshwater. Rivers provide accessible water for ecosystems and human use, while aquifers store water underground, making it available for wells and springs. Glaciers, as large ice formations, hold substantial freshwater reserves that can feed rivers and lakes as they melt. In contrast, oceans are primarily saline and not suitable for direct human consumption or most agricultural uses. Therefore, they do not qualify as sources of freshwater, making options A, B, and D the correct choices.
A teacher is introducing the geologic time scale to third-grade students. She tells them that the entire history of Earth, from its formation to the present day, was 24 hours long, with 12:00 midnight representing the time of the formation of Earth and 12:00 midnight the following night representing the present day. About what time did humans appear in this 24-hour time scale?
- A. 11:58 PM
- B. 9:00 PM
- C. 6:00 PM
- D. 1:00 PM
Correct Answer & Rationale
Correct Answer: A
In this 24-hour analogy of Earth's history, humans appeared very recently, approximately 200,000 years ago, which is just a fraction of the total time. This corresponds to 11:58 PM, indicating that humans emerged just two minutes before the "midnight" representing the present day. Option B (9:00 PM) suggests a much earlier appearance, which does not align with the scientific timeline of human evolution. Option C (6:00 PM) is even earlier, placing humans in a time when dinosaurs were still prominent. Option D (1:00 PM) is far too early, as it would imply humans existed when early mammals were just beginning to evolve. Thus, only 11:58 PM accurately reflects the brief time humans have existed in the context of Earth's history.
In this 24-hour analogy of Earth's history, humans appeared very recently, approximately 200,000 years ago, which is just a fraction of the total time. This corresponds to 11:58 PM, indicating that humans emerged just two minutes before the "midnight" representing the present day. Option B (9:00 PM) suggests a much earlier appearance, which does not align with the scientific timeline of human evolution. Option C (6:00 PM) is even earlier, placing humans in a time when dinosaurs were still prominent. Option D (1:00 PM) is far too early, as it would imply humans existed when early mammals were just beginning to evolve. Thus, only 11:58 PM accurately reflects the brief time humans have existed in the context of Earth's history.
The speed of light in empty space, that is, a vacuum, is 300,000 km/s. The speed of sound in empty space is:
- B. greater than 0 but less than 300,000 km/s
- C. 300,000 km/s
- D. greater than 300,000 km/s
Correct Answer & Rationale
Correct Answer: A
The speed of sound requires a medium, such as air or water, to propagate; it cannot travel through a vacuum. Therefore, the speed of sound in empty space is effectively zero. Option B suggests that the speed of sound is greater than 0 but less than 300,000 km/s, which is incorrect because sound cannot exist in a vacuum. Option C states it is 300,000 km/s, which misrepresents sound's nature, as this speed is specific to light. Option D claims it is greater than 300,000 km/s, which is impossible since sound cannot travel in a vacuum at all. Thus, the only valid conclusion is that the speed of sound in empty space is zero.
The speed of sound requires a medium, such as air or water, to propagate; it cannot travel through a vacuum. Therefore, the speed of sound in empty space is effectively zero. Option B suggests that the speed of sound is greater than 0 but less than 300,000 km/s, which is incorrect because sound cannot exist in a vacuum. Option C states it is 300,000 km/s, which misrepresents sound's nature, as this speed is specific to light. Option D claims it is greater than 300,000 km/s, which is impossible since sound cannot travel in a vacuum at all. Thus, the only valid conclusion is that the speed of sound in empty space is zero.
Of the following gases, which is found in the atmosphere in the greatest concentration?
- A. O2
- B. N2
- C. H2
- D. CO2
Correct Answer & Rationale
Correct Answer: B
Nitrogen (N2) constitutes about 78% of the Earth's atmosphere, making it the most abundant gas. Oxygen (O2), while essential for life, is present at around 21%, significantly less than nitrogen. Hydrogen (H2) is found in trace amounts and is not a major component of the atmosphere. Carbon dioxide (CO2) is also present in much smaller concentrations, approximately 0.04%, and is primarily significant for its role in climate regulation. Therefore, nitrogen is the predominant gas, while the others are present in much lower concentrations.
Nitrogen (N2) constitutes about 78% of the Earth's atmosphere, making it the most abundant gas. Oxygen (O2), while essential for life, is present at around 21%, significantly less than nitrogen. Hydrogen (H2) is found in trace amounts and is not a major component of the atmosphere. Carbon dioxide (CO2) is also present in much smaller concentrations, approximately 0.04%, and is primarily significant for its role in climate regulation. Therefore, nitrogen is the predominant gas, while the others are present in much lower concentrations.